NAME¶
mod_auth_tkt - apache ticket authentication module
DESCRIPTION¶
mod_auth_tkt is a lightweight cookie-based authentication module, written in C,
for apache versions 1.3.x, 2.0.x, and 2.2.x It implements a single-signon
framework that works across multiple apache instances, different apache
versions, and multiple machines.
mod_auth_tkt itself is completely repository-agnostic, as the actual
authentication is done by a user-supplied CGI or script in your language of
choice (examples are provided in Perl, with contrib libraries for use with
python and PHP). This allows authentication against virtually any kind of user
repository you can imagine (password files, ldap directories, databases, etc.)
mod_auth_tkt supports inactivity timeouts (including the ability to control how
aggressively the ticket is refreshed), the ability to include arbitrary user
data within the cookie, configurable cookie names and domains, token-based
access to subsections of a site, and optional 'guest' access for
unauthenticated users.
CONFIGURATION¶
mod_auth_tkt is configured in your apache configuration files using the
following set of directives (all mod_auth_tkt directives begin with
'TKTAuth'):
Server Directives¶
mod_auth_tkt supports two apache server-level directives, one required -
TKTAuthDigest, the shared secret used for digest hashing - and one optional -
TKTAuthDigestType, the type of digest to use in ticket hashes. Both may be
global or specific to a virtual host.
- TKTAuthSecret <secret>
- String - the secret used for digest hashing. This should be
kept secret and changed periodically. e.g.
TKTAuthSecret "w b@5b15#664038f.f9d8U19b7e25 664eY9ad2%4393e,a2ef"
- TKTAuthDigestType [ MD5 | SHA256 | SHA512 ]
- String, one of MD5 | SHA256 | SHA512. The digest/hash type
to use in tickets. The default is MD5, which is faster, but has now been
shown to be vulnerable to collision attacks. Such attacks are not directly
applicable to mod_auth_tkt, which primarily relies on the security of the
shared secret rather than the strength of the hashing scheme. More
paranoid users will probably prefer to use one of the SHA digest types,
however.
The default is likely to change in a future version, so setting the digest
type explicitly is encouraged.
Note that using one of the SHA digest types with the perl CGI scripts
requires a version of Apache::AuthTkt >= 2.1.
Directory Directives¶
All directory-level directives are optional, except that either TKTAuthLoginURL
or TKTAuthGuestLogin (or both) must be set to cause mod_auth_tkt to be invoked
for a particular directory. As usual, directory-level directives may be set in
Directory or Location sections, or in .htaccess files.
- AuthType None / require <users>
- mod_auth_tkt requires the following standard apache
authentication directives to trigger authentication:
AuthType None
require valid-user # or require user1, user2, etc.
- TKTAuthLoginURL <url>
- Standard URL to which unauthenticated users are redirected.
This is a required directive unless you are using guest mode via
'TKTAuthGuestLogin on'. e.g.
TKTAuthLoginURL https://www.example.com/auth/login.cgi
- TKTAuthTimeoutURL <url>
- URL to which users are redirected in the event their ticket
times out. Default: TKTAuthLoginURL. e.g.
TKTAuthTimeoutURL https://www.example.com/auth/login.cgi?timeout=1
- TKTAuthPostTimeoutURL <url>
- URL to which users are redirected in the event their ticket
times out during a POST operation. This case is distinguished to allow you
to handle such cases specially - you probably don't want to redirect back
to the referrer after login, for instance. Default: TKTAuthTImeoutURL.
e.g.
TKTAuthPostTimeoutURL https://www.example.com/auth/login.cgi?posttimeout=1
- TKTAuthUnauthURL <url>
- URL to which users are redirected in the event that they
are not authorised for a particular area e.g. incorrect tokens.
TKTAuthUnauthURL https://www.example.com/auth/login.cgi?unauth=1
- TKTAuthGuestLogin <boolean>
- Flag to turn on 'guest' mode, which means that any user
without a valid ticket is authenticated anyway as the TKTAuthGuestUser
user. This is useful for allowing public access for guests and robots,
while allowing more personalised or privileged access for users who login.
Default: off. e.g.
TKTAuthGuestLogin on
- TKTAuthGuestCookie <boolean>
- Flag to indicate whether or not to issue a ticket cookie
for guest users. Issuing a cookie is primarily useful where you are using
UUID-ed guest users where you want them to keep the initial guest username
you issue them for tracking purposes. e.g.
TKTAuthGuestCookie on
Default is 'off', unless you use a TKTAuthGuestUser with a UUID (see next),
in which case it's 'on'. Setting explicitly is recommended, however.
- TKTAuthGuestUser <string>
- Username to be used for the guest user (in the ticket uid,
REMOTE_USER environment variable, etc).
On apache 2.0.x and 2.2.x (but not on apache 1.3.x), the TKTAuthGuestUser
may also contain a special sprintf-like pattern '%U', which is expanded to
36-character UUID, allowing individualised guest usernames. The %U may
also include an integer <= 36 to limit the number of characters used in
the UUID e.g. %12U, %20U etc.
Default: 'guest'. Examples:
TKTAuthGuestUser visitor
TKTAuthGuestUser guest-%12U
- TKTAuthGuestFallback <boolean>
- Flag to indicate that a timed out user ticket should
automatically fallback to 'guest' status, and issue a new guest ticket,
instead of redirecting to the TKTAuthTimeoutURL. Only makes sense with
TKTAuthGuestLogin on, of course.
Default: off.
- TKTAuthTimeout <seconds>
- The ticket timeout period, in seconds. After this period,
the ticket is considered stale, and the user is redirected to the
TKTAuthTimeoutURL (if set, else to the TKTAuthLoginURL). Note that the
ticket can be automatically refreshed, however, using the next setting.
The following units can also be specified on the timeout (with no spaces
between timeout and unit): y/years, M/months, w/weeks, d/days, h/hours,
m/minutes, and s/seconds.
This timeout is protected by the ticket hashing, so cannot be trivially
modified, unlike the TKTAuthCookieExpires setting below.
Setting TKTAuthTimeout to 0 means never timeout, but this is strongly
discouraged, as it allows for trivial replay attacks. Set it to a week or
two if you really don't want timeouts.
Default: 2h. Examples:
TKTAuthTimeout 86400
TKTAuthTimeout 1w
TKTAuthTimeout 1w 4d 3h
- TKTAuthTimeoutRefresh <decimal>
- A number between 0 and 1 indicating whether and how to
refresh ticket timestamps. 0 means never refresh (hard timeouts). 1 means
refresh tickets every time. .33 (for example) means refresh if less than
.33 of the timeout period remains.
This is a politeness setting for those paranoid types who have their
browsers set to confirm all cookies - refreshing every time quickly
becomes VERY tedious. Default: 0.5. e.g.
TKTAuthTimeoutRefresh 0.66
- TKTAuthCookieName <name>
- The name used for the ticket cookie. Default:
'auth_tkt'.
- TKTAuthDomain <domain>
- The domain to use in ticket cookies, which defines the
hosts for which the browser will submit this cookie. Default: the apache
ServerName (either global or for a specific virtual host).
- TKTAuthCookieExpires <seconds>
- NB: This directive is not currently supported on
apache 1.3.x!
The period until the cookie expires, used to set the 'expires' field on the
ticket cookie, in seconds. This is useful if you want cookies to persist
across browser sessions (and your login script must support it too, of
course).
The following units can also be specified on the expiry period (with no
spaces between period and unit): y/years, M/months, w/weeks, d/days,
h/hours, m/minutes, and s/seconds.
Note that his is a client-side setting and is not protected by the
ticket hashing, so you should always set a TKTAuthTimeout in addition to
using an expiry. Cookie expiries are refreshed with tickets if
TKTAuthTimeoutRefresh is set.
Default: none. Examples:
TKTAuthCookieExpires 86400
TKTAuthCookieExpires 1w
TKTAuthCookieExpires 1w 3d 4h
- TKTAuthBackArgName <name>
- The name used for the back GET parameter. If this is set,
mod_auth_tkt will add a GET parameter to all redirect URLs containing a
URI-escaped version of the current requested page e.g. if the requested
page is http://www.example.com/index.html and TKTAuthBackArgName is set to
'back', mod_auth_tkt will add a parameter like:
back=http%3A%2F%2Fwww.example.com%2Findex.html
to the TKTAuthLoginURL it redirects to, allowing your login script to
redirect back to the requested page upon successful login. Default:
'back'.
- TKTAuthBackCookieName <name>
- The cookie name to use for the back cookie. If this is set,
mod_auth_tkt will set a back cookie containing a URI-escaped version of
current requested page when redirecting (see TKTAuthBackArgName above).
Default: none.
- TKTAuthToken <token>
- String indicating a required token for the given location,
implementing a simple form of token-based access control. If the user's
ticket does not contain one or more of the required tokens in the ticket
token list then mod_auth_tkt will redirect to the TKTAuthUnauthURL
location (or TKTAuthLoginURL if not set). Your login script is expected to
set the appropriate token list up at login time, of course.
Note that this directive can be repeated, and the semantics are that
any of the required tokens is sufficient for access i.e. the tokens
are ORed.
Default: none. e.g.
TKTAuthToken finance
TKTAuthToken admin
- TKTAuthIgnoreIP <boolean>
- Flag indicating that mod_auth_tkt should ignore the client
IP address in authenticating tickets (your login script must support this
as well, setting the client IP address to 0.0.0.0). This is often required
out on the open internet, especially if you are using an HTTPS login page
(as you should) and are dealing with more than a handful of users (the
typical problem being transparent HTTP proxies at ISPs). Default: 'off'
i.e. ticket is only valid from the originating IP address. e.g.
TKTAuthIgnoreIP on
- TKTAuthRequireSSL <boolean>
- Flag used to indicate that tickets should be refused except
in SSL/HTTPS protected contexts (redirects to TKTAuthLoginURL if not,
which presumably would be using HTTPS). Default: 'off' ( don't
require SSL). e.g.
TKTAuthRequireSSL on
See also TKTAuthCookieSecure below.
- TKTAuthCookieSecure <boolean>
- Flag used to set the 'secure' flag on all ticket cookies
issued, indicating to the browser that they should only be sent in
SSL/HTTPS protected contexts. Default: 'off' ( don't set 'secure'
flag). e.g.
TKTAuthCookieSecure on
TKTAuthRequireSSL and TKTAuthCookieSecure are normally used together. One
case where it makes sense to use them separately is where you are proxying
through a separate SSL-equipped reverse proxy, where you would want to use
TKTAuthCookieSecure by itself (since the proxied request will never be via
SSL).
- TKTAuthDebug <integer>
- Turn on mod_auth_tkt debug output messages in your error
log, with verbosity increasing with higher integer values. Current range:
1-3.
Note that you will also require apache 'LogLevel debug' set to see these
messages.
EXAMPLES¶
Minimal config using logins:
<Location /secret1>
AuthType None
require valid-user
TKTAuthLoginURL https://www.example.com/auth/login.cgi
</Location>
Minimal config using guest logins (users can still login explicitly, of course):
<Location /secret2>
AuthType None
require valid-user
TKTAuthGuestLogin on
</Location>
Example internet configuration:
<Location /secret3>
AuthType None
require valid-user
TKTAuthLoginURL https://www.example.com/auth/login.cgi
TKTAuthTimeoutURL https://www.example.com/auth/login.cgi?timeout=1
TKTAuthPostTimeoutURL https://www.example.com/auth/login.cgi?timeout=1&post=1
TKTAuthIgnoreIP on
TKTAuthTimeout 2h
TKTAuthCookieExpires 2h
</Location>
Example intranet configuration:
<Location /secret4>
AuthType None
require valid-user
TKTAuthGuestLogin on
TKTAuthLoginURL https://www.example.com/auth/login.cgi
TKTAuthTimeoutURL https://www.example.com/auth/login.cgi?timeout=1
TKTAuthPostTimeoutURL https://www.example.com/auth/login.cgi?timeout=1&post=1
TKTAuthTimeout 4h
TKTAuthCookieExpires 4h
</Location>
SUPPORT¶
Support is available on the mod_auth_tkt mailing list, courtesy of sourceforge:
- List
- modauthtkt-users@lists.sourceforge.net
- List Page and Signup
- https://lists.sourceforge.net/lists/listinfo/modauthtkt-users
- List Archive
- http://sourceforge.net/mailarchive/forum.php?forum=modauthtkt-users
BUGS¶
Ticket payload should include IP address, to make debugging IP address problems
easier.
AUTHOR¶
Gavin Carr <gavin@openfusion.com.au>
LICENCE¶
mod_auth_tkt is licensed under the terms of the Apache Licence.